The invention relates to a sewing machine, and more particularly relates to a selecting device of a double-function sewing machine which may produce different types of stitches, such as the ordinary lock stitches and the overlock stitches. The invention is directed to a sewing machine such as disclosed in the copending U.S. Pat. application Ser. No. 860,589 U.S. Pat. No. 4,267,786 which is provided with two separate stitch forming mechanisms for different types of stitches, each operatively and selectively connected through a transmission device to a single drive source such as a machine driving motor.
According to the invention, a selecting device is manually and selectively operated from an external dial to activate a clutch to connect one of the stitch forming mechanisms to the machine drive motor and at the same time to inactivate another clutch to disconnect the other of the stitch forming mechanisms from the machine driving motor. In addition, both stitch forming mechanisms are disconnected from the machine driving motor if a thread winding mechanism of the sewing machine is operated.
So far, home sewing machines have been structured only to produce lock stitches. Recently it has been generally desired to have a sewing machine which functions to provide lock stitching and overlock stitching which are indispensable for producing a well finished stitching work, and accordingly various constructions regarding such a sewing machine have been provided. However, since the sewing machine requires two different types of stitch forming mechanisms, it becomes bulky, complex in structure and difficult to operate, and also awkward in design.